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How to configure a port on our core switch for a server

I am looking for some guidance on how to configure a server port on our core switch. For some options, I was thinking this:

Option A

no switchport

no ip address

 

Option B

switchport

switchport access

switchport access vlan 105

or does this accomplish the same thing? 

 

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Accepted Solutions

Hi

Second option is the right one. First option will not work. If you issue no switch on the interface, the interface will be configured as Layer3 interface and one IP address is expected.

With the second option you keep the interface as Layer2 and use the AVI as gateway for your server.

One good practice is add the command "spanning-tree portfast " on this interface. This way if the interface flaps, it will come up faster.

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9 Replies 9

I should also say there is an SVI configured for 105 and the server has an IP within that range already. 

Hi

Second option is the right one. First option will not work. If you issue no switch on the interface, the interface will be configured as Layer3 interface and one IP address is expected.

With the second option you keep the interface as Layer2 and use the AVI as gateway for your server.

One good practice is add the command "spanning-tree portfast " on this interface. This way if the interface flaps, it will come up faster.

you said "one IP address is expected" isn't the one IP address the IP of the server? I guess this is what was confusing me. I do know typically if you do a no switchport you put an IP on the port itself. 

Joseph W. Doherty
Hall of Fame
Hall of Fame

Usually option B, and the two options are not the same thing.

Thanks for your reply! Also, how so? 

"Also, how so?"

As in, why not the same?

If so, your option A defined a "routed" port, i.e. much like a router would use.  Such a port should have an IP directly assigned to it.  (You later ask, wouldn't the server have an IP.  Yes it would, but it needs a gateway IP to reach other hosts not on the same network.  This is what the IP on such a port would provide.  I.e. without an IP on such a port, it's, more-or-less, useless.)

Option B creates a VLAN port, which allows multiple hosts to use and be on the same L2 broadcast domain.  (Again, for hosts on the VLAN, they will need a gateway IP to get on/off that VLAN.  On a L3 switch, often a SVI provides that, but a router or L3 switch "routed" port [option A] might provide a GW IP too.  [In theory, on the same L3 switch, you could connect your server, and other hosts, to access ports, same VLAN, and then connect an access port, same VLAN, to a "routed" port, with IP, on the same L3 switch.  Using an SVI, instead, not only saves using two physical ports, a SVI should be able to handle the aggregate bandwidth of all its ports assigned to its VLAN.])

Thanks for the informative comment! I do appreciate it. I do know this stuff I guess I was confused looking at how the other ports were configured. Thank you! 

do you have only one server or server farm ?

Option A

no switchport <<- this make the port L3 port and no need SVI any more 

no ip address

 

Option B

switchport

switchport access

switchport access vlan 105 <<- this keep port L2 and you need SVI for VLAN 105 

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